In the 3rd Generation Partnership Project (3GPP), a radio access scheme (Evolved Universal Terrestrial Radio Access (EUTRA)) and a radio access network (Evolved Universal Terrestrial Radio Access Network (EUTRAN)) for cellular mobile communication have been considered. The EUTRA and the EUTRAN are also referred to as Long Term Evolution (LTE). In LTE, a base station apparatus is also referred to as an evolved NodeB (eNodeB) and a terminal device is also referred to as a User Equipment (UE). LTE is a cellular communication system in which an area is divided in a cellular pattern into multiple cells, each being served by a base station apparatus. A single base station apparatus may manage multiple cells.
In 3GPP, Proximity based Services (ProSe) have been considered. ProSe includes ProSe discovery and ProSe communication. The ProSe discovery is a process which specifies that a terminal device is brought in proximity to a different terminal device using the EUTRA. The ProSe communication is communication between two terminal devices that are brought in proximity to each other using a EUTRAN communication path that is established between the two terminals. For example, the communication path may be established directly between the terminal devices.
The ProSe discovery and the ProSe communication are also referred to as Device to Device (D2D) discovery and D2D communication, respectively. The ProSe discovery and the ProSe communication are also collectively referred to as ProSe. The D2D discovery and the D2D communication are also collectively referred to as D2D. The communication path is also referred to as a link.
In NPL 1, it is disclosed that a subset of resource blocks are reserved for the D2D, that a network configures a set of D2D resources, and that the terminal device is allowed to transmit a D2D signal using the configured resources.